Common problems by part
Mercedes-Benz GLB lights and electrics problems
DVSA MOT tests 2022–2025 · 12,047 MOT tests · Updated
At 3 years, 1.4 in 100 MOT tests of the Mercedes-Benz GLB failed on lights and electrics, against 2.9 for all class 4 vehicles the same age (all test years; 12,047 MOT tests) [1].
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- Against all class 4 vehicles the same age: about average for all class 4 vehicles the same age (all test years), 170 MOT tests with a fail
- By age: seen at 3 ages from 3 to 5 years, 21,415 MOT tests
- Most common fail: Headlight aimed too high, 0.7 per 100 MOT tests
Figures are for the model as a whole, not for one car.
What the MOT tests show
What we know
1.4 fails per 100 MOT tests at 3 years, against 2.9 for all class 4 vehicles tested at 3 (all test years). That is about average.
Why it matters
A lights and electrics fail stops the car passing until it is fixed; the most common one is rated major by DVSA.
What to check
Walk round with the lights, indicators, brake lights and hazards on (ask someone to press the pedal) and check every dashboard warning light goes out after starting.
Mercedes-Benz GLB lights and electrics fails by age
| Age | MOT tests | Fails per 100 | All class 4 vehicles the same age |
|---|---|---|---|
| 3 | 12,047 | 1.4 | 2.9 |
| 4 | 6,756 | 1.6 | 3.1 |
| 5 | 2,612 | 2.0 | 3.7 |
All first-use years of the Mercedes-Benz GLB pooled at each age, against all class 4 vehicles at that age over all 2022–2025 test years.
What fails in the lights and electrics at 3 years
Fails
- Headlight aimed too high: 0.7 fails per 100 MOT tests, all class 4 vehicles 0.9. Adjust headlamp aim: estimated £16–£39 (0.2–0.5 h at £78/h (ONS local-garage repair quotes, 1,058 quotes from 65 garages, Sep 2025 to Aug 2026) + parts) Headlamp aim too high MOT fail
- Headlamp aim: too low: 0.3 fails per 100 MOT tests, all class 4 vehicles 0.6. Adjust headlamp aim: estimated £16–£39 (0.2–0.5 h at £78/h (ONS local-garage repair quotes, 1,058 quotes from 65 garages, Sep 2025 to Aug 2026) + parts) Headlamp aim too low MOT fail
- Horn: not working: 0.2 fails per 100 MOT tests, all class 4 vehicles 0.1. Repair or replace horn: estimated £33–£113 (0.3–1 h at £78/h (ONS local-garage repair quotes, 1,058 quotes from 65 garages, Sep 2025 to Aug 2026) + parts £10–£35) Horn not working MOT fail
Repair figures are estimates, not quotes: how we estimate repair costs.
Buying a Mercedes-Benz GLB? Check that exact car before the viewing.
Buying Report £14.99 incl. VAT · one car · no subscription · Not a mechanical inspection.
- Model risks for this year and fuel
- What similar cars did at their next MOT
- Repairs ahead
- Viewing checklist
How to check on a test drive
Walk round with the lights, indicators, brake lights and hazards on (ask someone to press the pedal) and check every dashboard warning light goes out after starting.
Check one Mercedes-Benz GLB, not the average
The figures here describe Mercedes-Benz GLB cars as a group. These free tools answer for one car. Each line says what the tool reads.
- Check a Mercedes-Benz GLB's MOT history Every MOT test, fail item, advisory and mileage reading DVSA holds for that registration.
- MOT advisory checker Paste an advisory or defect to read DVSA's wording, its grade and what tends to happen at the next MOT.
Other Mercedes-Benz GLB problems
Lights and electrics on rival models
- Hyundai Tucson lights and electrics problems: 1.7 per 100 MOT tests at 3 years, against 1.4 for the Mercedes-Benz GLB (91,328 MOT tests)
- Volvo XC40 lights and electrics problems: 1.5 per 100 MOT tests at 3 years, against 1.4 for the Mercedes-Benz GLB (82,664 MOT tests)
- Vauxhall Grandland lights and electrics problems: 2.3 per 100 MOT tests at 3 years, against 1.4 for the Mercedes-Benz GLB (61,758 MOT tests)
Questions people ask
Does the Mercedes-Benz GLB have more lights and electrics problems than other cars?
1.4 in 100 MOT tests at 3 years, against 2.9 for all class 4 vehicles the same age: about average by our test (all test years; 12,047 MOT tests).
How common are Mercedes-Benz GLB lights and electrics problems?
1.4 in 100 MOT tests at 3 years failed on lights and electrics, against 2.9 for all class 4 vehicles the same age (all test years; 12,047 MOT tests).
What is the most common Mercedes-Benz GLB lights and electrics fail?
0.7 in 100 MOT tests at 3 years: Headlight aimed too high (79 MOT tests with it).
Sources
- Driver and Vehicle Standards Agency, Anonymised MOT tests and results, 2022 to 2025. DVSA MOT data, Open Government Licence v3.0, 21,415 MOT tests. Accessed 7 Oct 2026.
- Office for National Statistics, Consumer price inflation, local price quotes (car repair items). ONS price quotes, series 610236. Accessed 7 Oct 2026.
Parts: against all class 4 vehicles at the same age, all 2022–2025 test years pooled, not adjusted for mileage. Breakdowns and non-MOT faults are not in this data. How we compare